Determination of Fe SMK Negeri 13 Bandung

Procedure Weigh out accurately sufficient of the sample to contain 140 mg of Iron, rinse into a 500mL beaker covered with a clock glass and provided with a stirring rod. Teknologi dan Rekayasa

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Keep the resultant solution not more than 50 mL Repeat the rinsing process until the weighing bottle is clean with a few more water. Keep the resultant solution not more than 50 mL Teknologi dan Rekayasa

Add l0 mL of dilute hydrochloric acid (1 : 1) followed by about 1 or 2 mL of concentrated nitric acid Teknologi dan Rekayasa

Heat the mixture and boil gently for several minutes until the of the solution changes to intense yellow. Test the oxidation completeness with 1-2 drops of ammonia solution Rinse down the sides of the beaker and the clockglass, and dilute to 200 mL. Heat the solution to boiling. Teknologi dan Rekayasa

Add to the resultant hot solution (about 800 C) filtered dilute ammonia solution (1 : 1) drop wise and with stirring until the mixture is faintly alkaline . Teknologi dan Rekayasa

Heat the solution and boil for 1 minute Heat the solution and boil for 1 minute. After the precipitate has settled, pour the supernatant into a fitted filter paper on a funnel. Teknologi dan Rekayasa

Add 50 mL of washing solution (hot 1% NH4NO3), stir and let the precipitate settle. Pour the supernatant into filter paper. Teknologi dan Rekayasa

Clean the beaker glass with the policeman Repeat the washing process with another 50 mL of washing solution until the filtrate is chloride free Clean the beaker glass with the policeman Teknologi dan Rekayasa

Dry and char the filter paper When the moisture has been expelled, the flame is increased slightly so as to carbonize the paper slowly. Teknologi dan Rekayasa

When the paper has completely carbonized and vapors are no longer evolved, the flame is moved to the back (bottom) of the crucible and the carbon slowly burned off while the flame is gradually increased.* Teknologi dan Rekayasa

After all the carbon has been burned away, the crucible is covered completely (if desired, the crucible may be placed in a vertical position for this purpose) and heated to the required temperature by means of a Bunsen burner. Teknologi dan Rekayasa

When the ignition is ended, the flame is removed and, after 1-2 minutes, the crucible and lid are placed in a desiccator containing a suitable desiccant and allowed to cool for 25-30 minute Teknologi dan Rekayasa

The crucible and lid are then weighed. The crucible and contents are then ignited at the same temperature for 10-20 minutes, allowed to cool in a desiccator as before, and weighed again. Teknologi dan Rekayasa

Calculation Mass of Fe3+ = 2 x Ar Fe x mass of residue Mr Fe2O3 % Fe3+ = Mass of Fe3+ x 100 % Mass of sample Teknologi dan Rekayasa